Control method of laundry machine

ABSTRACT

The patent application discloses a control method of a laundry machine provided with a balancer. The method includes decreasing a speed of a drum ( 320 ) in case vibration of the drum ( 320 ) sensed in an accelerating step is a predetermined value or more and rotating the drum ( 320 ) at a constant speed for a predetermined time period to implement balancing.

TECHNICAL FIELD

The present invention relates to a control method of a laundry machine.

BACKGROUND ART

In general, a laundry machine may include washing, rinsing and spinningcycles. Here, the spinning cycle includes a rotating step of rotating adrum provided in such a laundry machine at the highest RPM. Because ofthe step, the spinning cycle would generate noise and vibration quite alot, which is required to be solved in the art the prevent inventionpertains to.

DISCLOSURE OF INVENTION Technical Problem

Accordingly, the present invention is directed to a control method of alaundry machine.

An object of the present invention is to provide a control method of alaundry machine which can solve the above problem.

Solution to Problem

To solve the problems, an object of the present invention is to providea control method of a laundry machine comprising a balancer, the controlmethod comprising decreasing a speed of a drum in case vibration of thedrum sensed in an accelerating step is a predetermined value or more androtating a drum at a constant speed for a predetermined time period toimplement balancing.

Advantageous Effects of Invention

The present invention has following advantageous effects.

According to the spinning cycle control method of the laundry machinedescribed above, if the vibration of the drum is a predetermined valueor more at the RPM higher than the transient region, the vibration ofthe drum may be reduced in the laundry machine having the vibration ofthe drum separated from that of the tub.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate embodiments of the disclosure andtogether with the description serve to explain the principle of thedisclosure.

In the drawings:

FIG. 1 is an exploded perspective view illustrating a laundry machineaccording to the present invention to which a control method is applied;

FIG. 2 is a sectional view illustrating a connection state of FIG. 1;

FIG. 3 is a graph illustrating a spinning control method according to afirst embodiment of the present invention;

FIG. 4 is a graph illustrating a spinning control method according to asecond embodiment of the present invention;

FIG. 5 is a graph showing a relation of mass vs. a natural frequency;and

FIG. 6 is a graph illustrating vibration characteristics of the laundrymachine of FIG. 2.

BEST MODE FOR CARRYING OUT THE INVENTION

As follows, an exemplary embodiment of the present invention will bedescribed in reference to the accompanying drawings. First of all, alaundry machine a control method according to an embodiment of thepresent invention can be applied to will be described and the controlmethod according to an embodiment of the present invention will bedescribed after that.

According to a laundry machine according to an embodiment, the tub maybe fixedly supported to the cabinet or it may be supplied to the cabinetby a flexible supporting structure such as a suspension unit which willbe described later. Also, the supporting of the tub may be between thesupporting of the suspension unit and the completely fixed supporting.

That is, the tub may be flexibly supported by the suspension unit whichwill be described later or it may be complete-fixedly supported to bemovable more rigidly. Although not shown in the drawings, the cabinetmay not be provided unlike embodiments which will be described later.For example, in case of a built-in type laundry machine, a predeterminedspace in which the built-in type laundry machine will be installed maybe formed by a wall structure and the like, instead of the cabinet. Inother words, the built-in type laundry machine may not include a cabinetconfigured to define an exterior appearance thereof independently.

In reference to FIGS. 1 and 2, a tub 12 provided in the laundry machineis fixedly supported to a cabinet. The tub 12 includes a tub front 100configured to define a front part of the tub and a tub rear 120configured to define a rear part of the tub. The tub front 100 and thetub rear 120 are assembled to each other by screws, to form apredetermined space big enough to accommodate the drum. The tub rear 120has an opening formed in a rear portion thereof and an innercircumference of the rear portion composing the tub rear 120 isconnected with an outer circumference of a rear gasket 250. The tub back130 has a through-hole formed in a center thereof to pass a shaft topass there through. The rear gasket 250 is made of a flexible materialnot to transmit the vibration of the tub back 130 to the tub rear 120.

The tub rear 120 has a rear surface 128 and the rear surface 128, thetub back 130 and the rear gasket 250 may define a rear wall of the tub.The rear gasket 250 is connectedly sealed with the tub back 130 and thetub rear 120, such that the wash water held in the tub may not leak. Thetub back 130 is vibrated together with the drum during the rotation ofthe drum. At this time, the tub back 130 is distant from the tub rear120 enough not to interfere with the tub rear. Since the rear gasket 250is made of the flexible material, the tub back 130 is allowed torelative-move, without interference of the tub rear 120. The rear gasket250 may include a corrugated portion 252 extendible to a predeterminedlength to allow the relative-motion of the tub back 130.

A foreign substance preventing member 200 configured to prevent foreignsubstances from drawn between the tub and the drum may be connected to afront portion of the tub front 100. The foreign substance preventingmember 200 is made of a flexible material and it is fixed to the tubfront 100. Here, the foreign substance preventing member 200 may be madeof the flexible material identical to the material composing the reargasket 250. Hereinafter, the foreign substance preventing member 200will be referenced to as ‘front gasket’.

The drum 32 includes a drum front 300, a drum center and a drum back340. Balancers 310 and 330 may be installed in front and rear parts ofthe drum, respectively. The drum back 340 is connected with a spider 350and the spider 350 is connected with the shaft 351. The drum 32 isrotated in the tub 12 by a torque transmitted via the shaft 351.

The shaft 351 is directly connected with a motor 170, passing throughthe tub back 130. Specifically, a rotor 174 composing the motor 170 isdirectly connected with the shaft 351. a bearing housing 400 is securedto a rear portion of the tub back 130 and the bearing housing 400rotatably supports the shaft, located between the motor 170 and the tubback 130.

A stator 172 composing the motor 170 is secured to the bearing housing400 and the rotor 174 is located surrounding the stator 172. Asmentioned above, the rotor 174 is directly connected with the shaft 351.Here, the motor 170 is an outer rotor type motor and it is directlyconnected with the shaft 351.

The bearing housing 400 is supported via a suspension unit with respectto a cabinet base 600. The suspension unit 180 includes threeperpendicular supporters and two oblique supporters configured tosupport the bearing housing 400 obliquely with respect to a forward andrearward direction.

The suspension unit 180 may includes a first cylinder spring 520, asecond cylinder spring 510, a third cylinder spring 500, a firstcylinder damper 540 and a second cylinder damper 530.

The first cylinder spring 520 is connected between a first suspensionbracket 450 and the cabinet base 600. The second cylinder spring 510 isconnected between a suspension bracket 440 and the cabinet base 600.

The third cylinder spring 500 is directly connected between the bearinghousing 400 and the cabinet base 600.

The first cylinder damper 540 is inclinedly installed between the firstsuspension bracket 450 and a rear portion of the cabinet base. Thesecond cylinder damper 530 is inclinedly installed between the secondsuspension bracket 440 and a rear portion of the cabinet base 600.

The cylinder springs 520, 510 and 500 of the suspension unit 180 may beelastically connected to the cabinet base 600 enough to allow aforward/rearward and rightward/leftward movement of the drum, notconnected to the cabinet base 600 fixedly. That is, they are elasticallysupported by the base 600 to allow the drum to be rotated to apredetermined angle in forward/rearward and rightward/leftwarddirections with respect to the connected portion.

The perpendicular ones of the suspension unit may be configured tosuspend the vibration of the drum elastically and the oblique ones maybe configured to dampen the vibration. That is, in a vibration systemincluding a spring and damping means, the perpendicular ones areemployed as spring and the oblique ones are employed as damping means.

The tub front 100 and the tub rear 120 are fixedly secured to thecabinet 110 and the vibration of the drum 32 is suspendedly supported bythe suspension unit 180. The supporting structure of the tub 12 and thedrum 32 may be called ‘separated’ substantially, such that the tub 12may not be vibrated even when the drum 32 is vibrated.

The bearing housing 400 and the suspension brackets may be connectedwith each other by first and second weights 431 and 430.

In case the drum 30 and 32 is rotated after the laundry 1 is loaded inthe drum 30 and 32 of the laundry machine according to the aboveembodiments, quite severe noise and vibration may be generated accordingto the position of the laundry 1. For example, when the drum 30 and 32is rotated in a state of the laundry not distributed in the drum 30 and32 uniformly (hereinafter, ‘unbalanced rotation’), much noise andvibration may be generated. Especially, if the drum 30 and 32 is rotatedat a high speed to spin the laundry, the noise and vibration may beproblematic.

Because of that, the laundry machine may include balancer 70, 310 and330 to prevent the noise and vibration generated by the unbalancedrotation of the drum 30 and 32. The balancer 70, 310 and 330 may beprovided in a front or rear portion, or in both of the portions of thedrum 30 and 32.

The balancers are mounted to the drum 30 and 32 to reduce the unbalance.Because of that, the balancer may have a movable gravity center. Forexample, the balancer may include movable bodies having a predeterminedweight located therein and a passage the movable bodies move along. Ifthe balancers may be ball balancers, the balancer 70, 310 and 330 mayinclude balls 72, 312 and 332 having a predetermined weight locatedtherein and a passage the ball moves along.

More specifically, the balls are rotated by the friction generatedduring the rotation of the drum 30 and 32 and they are not keptunmovable in the drum when the drum is rotated. Because of that, theballs are rotated at a different speed from the rotation speed of thedrum. Here, the laundry which generates the unbalance may be rotated atthe almost same speed as the speed of the drum because of the frictiongenerated by the close contact with an inner circumferential surface ofthe drum and the lifters provided in the inner circumferential surface.As a result, the rotation speed of the laundry is different from that ofthe balls. The rotation speed of the laundry is higher than that of theballs during an initial rotation stage in which the drum is rotated at arelatively low speed, specifically, a rotation angle speed of thelaundry is higher. In addition, a phase difference between the balls andthe laundry, which is a phase difference with respect to a rotationcenter of the drum, may changes continuously.

Hence, when the rotation speed of the drum is getting higher, the ballsmay be in close contact with an outer circumferential surface of thepassage by the centrifugal force. At the same time, the balls arealigned at a predetermined position having approximately 90° to 180° ofthe phase difference with respect to the laundry. If the rotation speedof the drum is a predetermined value or more, the centrifugal force isgetting larger and the friction generated between the outercircumferential surface and the balls is a predetermined value or moreand the balls may be rotated at the same speed as the drum. at thistime, the balls are rotated at the same speed as the drum, withmaintaining the position having the 90° to 180°, preferably,approximately 180° of the phase difference with respect to the laundry.In this specification of the present invention, the rotation of theballs at the predetermined positions as mentioned above may be expressedas ‘unbalance corresponding position’ or ‘balancing’.

As a result, in case load is concentrated on a predetermined portion ofthe drum inside by the laundry, the balls located in the balancers 70,310 and 330 may move to an unbalance corresponding position to reducethe unbalance.

Before describing a spinning control method according to an embodimentof the present invention, a characteristic of vibration generated in alaundry machine will be described as follows.

FIG. 6 is a graph showing a vibration of drum while the rotation speedof the drum increases.

First, vibration characteristics of the laundry machine according to theembodiment of the present invention will now be described with referenceto FIG. 6.

As the rotation speed of the drum is increased, a region (hereinafter,referred to as “transient vibration region”) where irregular transientvibration with high amplitude occurs is generated. The transientvibration region irregularly occurs with high amplitude before vibrationis transited to a steady-state vibration region (hereinafter, referredto as “steady-state region”), and has vibration characteristicsdetermined if a vibration system (laundry machine) is designed. Thoughthe transient vibration region is different according to the type of thelaundry machine, transient vibration occurs approximately in the rangeof 200 rpm to 270 rpm. It is regarded that transient vibration is causedby resonance. Accordingly, it is necessary to design the balancer byconsidering effective balancing at the transient vibration region.

In the mean time, as described above, in the laundry machine accordingto the embodiment of the present invention, the vibration source, i.e.,the motor and the drum connected with the motor are connected with thetub 12 through the rear gasket 250. Accordingly, vibration occurring inthe drum is little forwarded to the tub, and the drum is supported by adamping means and the suspension unit 180 via a bearing housing 400. Asa result, the tub 12 can directly be fixed to a cabinet 110 without anydamping means.

As a result of studies of the inventor of the present invention,vibration characteristics not observed generally have been found in thelaundry machine according to the present invention. According to thegeneral laundry machine, vibration (displacement) becomes steady afterpassing through the transient vibration region. However, in the laundrymachine according to the embodiment of the present invention a region(hereinafter, referred to as “irregular vibration”) where vibrationbecomes steady after passing through the transient vibration region andagain becomes great may be generated. For example, if the maximum drumdisplacement or more generated in an RPM band lower than the transientregion or the maximum drum displacement or more of steady state step ina RPM band higher than the transient region is generated, it isdetermined that irregular vibration is generated. Alternatively, if anaverage drum displacement in the transient region, +20% to −20% of theaverage drum displacement in the transient region or ⅓ or more of themaximum drum displacement in the natural frequency of the transientregion are generated, it may be determined that the irregular vibrationis generated.

However, as a result of the studies, irregular vibration has occurred ina RPM band higher than the transient region, for example has occurred ata region (hereinafter, referred to as “irregular vibration region”) inthe range of 350 rpm to 1000 rpm, approximately. Irregular vibration maybe generated due to use of the balancer, the damping system, and therear gasket. Accordingly, in this laundry machine, it is necessary todesign the balancer by considering the irregular vibration region aswell as the transient vibration region.

For example, the balancer is provide with a ball balancer, it ispreferable that the structure of the balancer, i.e., the size of theball, the number of balls, a shape of the race, viscosity of oil, and afilling level of oil are selected by considering the irregular vibrationregion as well as the transient vibration region. When considering thetransient vibration region and/or the irregular vibration region,especially considering the irregular vibration region, the ball balancerhas a greater diameter of 255.8 mm and a smaller diameter of 249.2. Aspace of the race, in which the ball is contained, has a sectional areaof 411.93 mm². The number of balls is 14 at the front and the rear,respectively, and the ball has a size of 19.05 mm. Silicon based oilsuch as Poly Dimethylsiloxane (PDMS) is used as the oil. Preferably, oilhas viscosity of 300 CS at a room temperature, and has a filling levelof 350 cc.

In addition to the structure of the balancer, in view of control, it ispreferable that the irregular vibration region as well as the transientvibration region is considered. For example, to prevent the irregularvibration, if the irregular vibration region is determined, thebalancing may be implemented at least one time before, while and afterthe drum speed passes the irregular vibration region. Here, if therotation speed of the drum is relatively high, the balancing of thebalancer may not be implemented properly and the balancing may beimplemented with decreasing the rotation speed of the drum. However, ifthe rotation speed of the drum is decreased to be lower than thetransient region to implement the balancing, it has to pass thetransient region again. In decreasing the rotation speed of the drum toimplement the balancing, the decreased rotation speed may be higher thanthe transient region.

As follows, a control method of the laundry machine having theconfiguration described above will be described. The laundry machineincludes the washing cycle, the rinsing cycle and the spinning cycle.According to the present invention, a spinning cycle control method willbe described in reference to the accompanying drawings.

FIG. 3 is a graph illustrating changes of RPM of the drum according tothe time passage. A horizontal axis of the graph shown in FIG. 3 is thetime and a vertical axis is the rotation speed of the drum 32, that is,RPM changes.

In reference to FIG. 3, the spinning cycle control method according tothe present invention includes a laundry distributing step (S100) and aspinning step (S200).

The laundry distributing step (S100) distributes the laundry loaded intothe drum uniformly, with rotating the drum at a relatively low speed.The spinning step (S200) rotates the drum at a relatively high speed andit removes the moisture from the laundry. However, such the laundrydistributing step and spinning step are named with respect to mainfunctions thereof. The functions of the steps may not be limited to thenames. For example, the laundry distributing step may remove themoisture of the laundry by using the rotation of the drum, as well asthe laundry distributing.

The laundry distributing step (S100) composing the control methodaccording to the present invention may include a wet laundry sensingstep (S110), a laundry disentangling step (S130) and an unbalancesensing step (S150). The spinning step (S200) may include a transientregion passing step (S210) and an accelerating step (S230). As follows,each one of the above steps will be described.

Once the rinsing cycle is completed, the laundry located in the drum 32is wet by the moisture. A control part senses the amount of the laundry,that is, the amount of the wet laundry located in the drum 32, when thespinning cycle is put into operation (S110).

The reason why the amount of the wet laundry is that the amount of thedry laundry measured in an initial stage of the washing cycle isdifferent from the amount of the wet laundry containing the moisture.The sensed amount of the wet laundry may be used as an elementconfigured to determine an allowable condition of the drum acceleratingor to determine to re-implement the laundry distributing step afterdecreasing the speed of the drum 32 based on an unbalance condition inthe transient region passing step (S210).

According to the control method of the present invention, the amount ofthe wet laundry located in the drum 32 is measured in case the drum isrotated at a decreased speed after rotated at a constant speed ofapproximately 100 to 110 RPM reached by the acceleration for apredetermined time period. If the rotation speed of the drum isdecreased, rheostatic braking is used. Specifically, the amount of thewet laundry is measured by using the amount of acceleration periodrotation in accelerating the motor 170 configured to rotate the drum 32,the amount of the acceleration period rotation in decreasing the speedof the motor 170, and an applied DC voltage.

After measuring the amount of the wet laundry, the control part mayimplement the laundry disentangling step (S130) configured to distributethe laundry inside the drum uniformly.

The laundry disentangling step distributes the laundry located in thedrum 32 uniformly to prevent the laundry from concentrated on a specificregion inside the drum, which might increase the unbalance. If theunbalance is increased, noise and vibration will be increased in casethe RPM of the drum is heightened. The laundry disentangling stepaccelerates the drum in a predetermined single direction with apredetermined oblique and it is implemented until the RPM reaches arotation speed of the unbalance sensing step which will be describedlater.

Hence, the control part senses the unbalance of the drum (S150).

If the laundry is concentrated on a specific region inside the drum 32,not distributed uniformly, the unbalance is increased and the noise andvibration will be generated when the RPM of the drum 32 is heightened.Because of that, the control part senses the unbalance of the drum andit determines whether the drum is accelerated.

The unbalance sensing uses difference of the accelerated speeds duringthe rotation of the drum 32. That is, there is difference of theaccelerated speeds when the drum is rotated downward along the gravityand when it is rotated upward reversely according to the level of thegenerated unbalance. The control part measures the difference of theaccelerated speeds by using a speed sensor, for example, a hall sensorprovided in the motor 170 to sense the amount of the unbalance. In casethe unbalance is sensed, the laundry located inside the drum keeps theclose contact with the inner circumferential surface of the drum,without dropped from the inner circumferential surface, even during therotation of the drum. The case having the drum rotated at approximately100 to 110 RPM is corresponding to this case.

If the drum is accelerated at a high speed in case the sensed unbalanceamount of the drum having a predetermined amount of wet laundry is areference unbalance value or more, the vibration and noise of the drumwill increase remarkably and it is difficult to accelerate the speed ofthe drum. Because of that, the control part may store a referenceunbalance value, which allows the acceleration of the speed according tothe amount of the wet laundry as a table typed data. After that, thecontrol part applies the sensed wet-laundry amount and the unbalanceamount to the table and it determines whether the speed of the drum isaccelerated. That is, in case the unbalance amount sensed according tothe sensed wet-laundry amount is the reference unbalance value or more,it can be determined that the unbalance amount is too much to acceleratethe drum speed and the above wet-laundry sensing, laundry disentanglingand unbalance sensing steps are repeated.

As mentioned above, the repetition of the wet laundry sensing step, thelaundry disentangling step and the unbalance sensing step may becontinued until the sensed unbalance amount meets less than thereference unbalance value. However, if the laundry machine is in anabnormal state or the laundry is entangled severely inside the drum, thesensed unbalance amount cannot meet less tan the reference unbalancevalue and the steps may be repeated. As a result, it is preferable thatthe control part controls the drum to stop the rotation and notifies theuser that the spinning cycle is not completed normally, if the speed ofthe drum fails to be accelerated for a predetermined time period, forexample, approximately more than 20 to 30 minutes after the spinningcycle starts.

In case the unbalance amount sensed according to the sensed wet laundryamount is less than the reference unbalance amount, the RPM acceleratingcondition is satisfied and the control part implements the transientregion passing step (S210).

Here, the transient region is a predetermined RPM band including atleast one resonance frequency which generates resonance according to thesystem of the laundry machine. When the system of the laundry machine isdetermined, the transient region is a unique vibration propertygenerated according to the determined system. The transient region isvariable according to the system of the laundry machine. For example,the transient region includes a scope of approximately 200 to 270 RPM inthe laundry according to the first embodiment and a scope ofapproximately 200 to 350 RPM in the laundry machine according to thesecond embodiment.

FIG. 5 illustrates a graph showing a relation of mass vs. a naturalfrequency. It is assumed that, in vibration systems of two laundrymachines, the two laundry machines have mass of m0 and m1 respectivelyand maximum holding laundry amounts are Δm, respectively. Then, thetransition regions of the two laundry machines can be determined takingΔnf0 and Δnf1 into account, respectively. In this instance, amounts ofwater contained in the laundry will not be taken into account, for thetime being.

In the meantime, referring to FIG. 5, the laundry machine with smallermass m1 has a range of the transition region greater than the laundrymachine with greater mass m0. That is, the range of the transitionregion having variation of the laundry amount taken into account becomesthe greater as the mass of the vibration system becomes the smaller.

The ranges of the transition regions will be reviewed on the related artlaundry machine and the laundry machine of the embodiment.

The related art laundry machine has a structure in which vibration istransmitted from the drum to the tub as it is, causing the tub tovibrate. Therefore, in taking the vibration of the related art laundrymachine into account, the tub is indispensible. However, in general, thetub has, not only a weight of its own, but also substantial weights at afront, a rear or a circumferential surface thereof for balancing.Accordingly, the related art laundry machine has great mass of thevibration system.

Opposite to this, in the laundry machine of the embodiment, since thetub, not only has no weight, but also is separated from the drum in viewof a supporting structure, the tub may not be put into account inconsideration of the vibration of the drum. Therefore, the laundrymachine of the embodiment may have relatively small mass of thevibration system.

Then, referring to FIG. 5, the related art laundry machine has mass m0and the laundry machine of the embodiment has mass m1, leading thelaundry machine of the embodiment to have a greater transition region,at the end.

Moreover, if the amounts of water contained in the laundry are takeninto account simply, Δm in FIG. 5 will become greater, making a rangedifference of the transition regions even greater. And, since, in therelated art laundry machine, the water drops into the tub from the drumeven if the water escapes from the laundry as the drum rotates, anamount of water mass reduction come from the spinning is small. Sincethe laundry machine of the embodiment has the tub and the drum separatedfrom each other in view of vibration, the water escaped from the druminfluences the vibration of the drum, instantly. That is, the influenceof a mass change of the water in the laundry is greater in the laundrymachine of the embodiment than the related art laundry machine.

Under above reason, though the related art laundry machine has thetransition region of about 200˜270 rpm, A start RPM of the transientregion of the laundry machine according to this embodiment may besimilar to a start RPM of the transient region of the conventionallaundry machine. An end RPM of the transient region of the laundrymachine according to this embodiment may increase more than a RPMcalculated by adding a value of approximately 30% of the start RPM tothe start RPM. For example, the transient region finishes at an RPMcalculated by adding a value of approximately 80% of the start RPM tothe start RPM. According to this embodiment, the transient region mayinclude a RPM band of approximately 200 to 350 rpm.

In the meantime, by reducing intensity of the vibration of the drum,unbalance may be reduced. For this, even laundry spreading is performedfor spreading the laundry in the drum as far as possible before therotation speed of the drum enters into the transition region.

In a case, a balancer is used, a method may be put into account, inwhich the rotation speed of the drum passes through the transitionregion while movable bodies provided in the balancer are positioned onan opposite side of an unbalance of the laundry. In this instance, it ispreferable that the movable bodies are positioned at exact opposite ofthe unbalance in middle of the transition region.

However, as described above, the transient region of the laundry machineaccording to this embodiment is relatively wide in comparison to that ofthe conventional laundry machine. Because of that, even if the laundryeven-spreading step or ball balancing is implemented in a RPM band lowerthan the transient region, the laundry might be in disorder or balancingmight be failed with the drum speed passing the transient region.

As a result, balancing may be implemented at least one time in thelaundry machine according to this embodiment before and while the drumspeed passing the transient region. Here, the balancing may be definedas rotation of the drum at a constant-speed for a predetermined timeperiod. Such the balancing allows the movable body of the balancer tothe opposite positions of the laundry, only to reduce the unbalanceamount. By extension, the effect of the laundry even-spreading.Eventually, the balancing is implemented while the drum speed passingthe transient region and the noise and vibration generated by theexpansion of the transient region may be prevented.

Here, when the balancing is implemented before the drum speed passingthe transient region, the balancing may be implemented in a differentRPM band from the RPM of the conventional laundry machine. For example,if the transient region starts at 200 RPM, the balancing is implementedin the RPM band lower than approximately 150 RPM. Since the conventionallaundry machine has a relatively less wide transient region, it is notso difficult for the drum speed to pass the transient region even withthe balancing implemented at the RPM lower than approximately 150 RPM.However, the laundry machine according to this embodiment has therelatively wide expanded transient region as described above. if thebalancing is implemented at the such the low RPM like in theconventional laundry machine, the positions of the movable bodies mightbe in disorder by the balancing implemented with the drum speed passingthe transient region. Because of that, the laundry machine according tothis embodiment may increase the balancing RPM in comparison to theconventional balancing RPM, when the balancing is implemented before thedrum speed enters the transient region. That is, if the start RPM of thetransient region is determined, the balancing is implemented in a RPMband higher than a RPM calculated by subtracting a value ofapproximately 25% of the start RPM from the start RPM. For example, thestart RPM of the transient region is approximately 200 RPM, thebalancing may be implemented in a RPM band higher than 150 RPm lowerthan 200 RPM.

Moreover, the unbalance amount may be measured during the balancing.That is, the control method may further include a step to measure theunbalance amount during the balancing and to compare the measuredunbalance amount with an allowable unbalance amount allowing theacceleration of the drum speed. If the measured unbalance amount is lessthan the allowable unbalance amount, the drum speed is accelerated afterthe balancing to be out of the transient region. In contrast, if themeasured unbalance amount is the allowable unbalance amount or more, thelaundry even-spreading step may be re-implemented. in this case, theallowable unbalance amount may be different from an allowable unbalanceamount allowing the initial accelerating.

That is, in case the rotation speed of the drum 32 passes the transientregion, the resonance is generated in the laundry machine and noise andvibration of the laundry machine are generated remarkably. The noise andvibration of the laundry machine will give an unpleasant feeling to theuser and they will interfere with the acceleration of the drum speed. Asa result, in case the rotation speed of the drum passes the transientregion, an acceleration inclination may be adjusted appropriately in thetransient region and to noise and vibration may be maintained as littleas possible during the acceleration of the drum 32.

Specially, the control part controls the speed of the drum to pass thetransient vibration region in the state of the balls located in theunbalance corresponding positions. If the sensed unbalance amount isless than the reference unbalance amount, the control part determines anacceleration point of the drum from the unbalance wave described above.

The centrifugal force is too small to implement the balancing at arotation speed below the transient vibration region. Because of that,the control part identifies the positions of the balls, with rotatingthe drum at a constant speed, and it accelerates the drum at apredetermined acceleration point to pass the transient vibration region.While the speed passing the transient region, the control part controlsthe balls to be located in opposite positions of the unbalance. That is,even though not implementing the balancing, the speed of the drum iscontrolled to pass the transient region while the balls are located inthe opposite position of the unbalance. For example, the speed iscontrolled to pass the transient region, with the angle between thelaundry generating unbalance and the balls being maintained at 90° ormore and it is preferable that that angles is 180° at an intermediateRPM of the transient region.

As a result, when accelerating the drum, with controlling the balancerdescribed above, the control part may store the acceleration pointallowing the speed to pass the transient region while the balls arelocated in the unbalance corresponding positions, as table data like thetable data including the wet laundry amount and the sensed unbalanceamount. That is, although the balls are not located in the unbalancecorresponding positions at the acceleration point, the balls are locatedin the unbalance corresponding positions during the passage of thetransient region. Preferably, the phase difference between the balls andthe laundry may be approximately 180° at the intermediate RPM of thetransient region. Because of that, the control part applies the sensedamount of the wet laundry and the amount of the unbalance to the tablementioned above while implementing the spinning cycle substantially.

As the drum 32 is accelerated while the RPM passing the transient regionor unexpected external shock is applied to the drum, the unbalanceamount of the drum 32 may be larger. If the unbalance amount of the drum32 is larger than a predetermined value, noise will be large remarkablyand it is difficult to accelerate the drum continuously. Because ofthat, the control part senses the unbalance amount of the drum 32continuously while the RPM passing the transient region.

In addition, the control part may control a vibration sensor provided inthe drum of the laundry machine to sense the vibration of the drum, inthe transient region. Especially, the tub provided in the laundrymachine having the vibration of the drum separated from that of the drummay be fixedly mounted and only the drum may be vibrated. Because ofthat, it is required to sense the vibration of the drum to prevent thecontact between the drum and the tub. If the vibration and/or theunbalance amount of the drum sensed in the transient region passing stepis a predetermined value or more, the control part decreases the RPM ofthe drum 32 and it repeats the wet laundry sensing step, the laundrydisentangling step and the unbalance sensing step which are describedabove.

After the transient region passing step, the control part implements theaccelerating step (S230). Once passing the transient region, the RPM ofthe drum 32 is accelerated at a relatively high speed to remove waterelements from the laundry. That is, the RPM of the drum 32 is increasedto a predetermined value and the moisture of the laundry inside the drum32 is removed, in the accelerating step (S230). However, theaccelerating step increases the RPM of the drum 32 at the high speed andnoise and vibration will be generated a lot in the laundry machine.Especially, the noise and vibration may be increasing in proportion tothe unbalance amount of the drum 32.

In the meanwhile, the laundry machine having the spinning cycle controlmethod applied thereto may include the balancer 310 and 330 configuredto prevent the noise and vibration generated by unbalance. The ballsprovided in the balancer 310 and 330 are configured move to theunbalance corresponding positions to reduce the unbalance amount. Here,the balls of the balancer may moveable more smoothly in the constant RPMthan the accelerated speed and in the relatively slow speed than in thehigh speed. Because of that, if the drum 32 is accelerated at therelatively high speed, the balls cannot move to the unbalancecorresponding positions smoothly. The spinning cycle control method mayinclude a step of moving the balls to move to the unbalancecorresponding positions, passing the transient region, namely, abalancing step.

In this case, the RPM used to implement the balancing may be set to behigher than the transient region of the laundry machine. The balancingis more and more advantageous to implement, as the RPM of the drum 32 isgetting lower. However, if the RPM is decreased below the transientregion again to implement the balancing, the noise and vibration may begenerated by resonance. As a result, the first balancing of the controlmethod may be implemented at a second RPM (RPM 2), for example, 350 to400 RPM.

After the first balancing step, the control part increases the RPM ofthe drum 32 to a target RPM, to remove the moisture from the laundry.Then, the control part controls the constant speed rotation of the drumto be embodied at the target RPM for a predetermined time period suchthat it may remove the moisture from the laundry smoothly.

In the first balancing step, the control part may sense the vibration ofthe drum. If the laundry machine includes a vibration sensor, thecontrol part may directly sense the vibration by using the vibrationsensor. Without the vibration sensor, the control part may directlysense the vibration of the drum by using the unbalance amount. If thesensed vibration of the drum is a predetermined value or more, thecontrol part decreases the speed of the drum and it repeats the wetlaundry sensing step, the laundry disentangling step and the unbalancesensing step which are described above.

In the meanwhile, the irregular vibration would be generated in theirregular vibration region according to the laundry machine as mentionedabove. In case the irregular vibration is generated, a control methodconfigured to reduce the irregular vibration will be described asfollows.

Specifically, when the laundry machine includes the vibration sensorconfigured to sense vibration, the control part may directly sense thevibration of the drum by using the vibration sensor. That is, thecontrol part receives a sensed vibration value from the vibration sensorand it compares the received vibration value with a preset referencevibration value. In case the sensed vibration value is the referencevibration value or more based on the result of the comparison, thecontrol parts determines that the irregular vibration is generated.Preferably, in case the vibration is continued at a predeterminedinterval for a predetermined time period or longer, the irregularvibration is determined to be generated.

If such the irregular vibration is generated, the control partimplements a second balancing (S234), without increasing the RPM of thedrum to the target RPM of the spinning cycle. Here, the RPM of thesecond balancing (S234) is a value higher than the transient region,approximately, 350 to 400 RPM, and the drum may beconstant-speed-rotated at that RPM approximately for 60 seconds.

The second balancing step (S234) enables the balls of the balancer tomove to the unbalance corresponding positions smoothly. Because of that,when the drum is reaccelerated, the vibration of the drum may be reducedas much as possible.

After the second balancing step, the control part re-accelerates thedrum and controls the vibration sensor to sense the vibration of thedrum simultaneously. In case the sensed vibration value of the drum isless than the predetermined value, the control part accelerates the drumup to the target RPM of the spinning cycle to remove the moisture fromthe laundry. In case the sensed vibration value of the drum is thepredetermined value or more, the control part re-implements the secondbalancing. Until the sensed vibration value is less than thepredetermined value, the control part re-implements the second balancingcontinuously. However, if the second balancing step is continued apredetermined number of times or more, the spinning cycle cannot becompleted and the spinning cycle time may be lengthened. Because ofthat, the control part controls the drum 32 to stop without acceleratingthe drum, in case the irregular vibration is generated in the drum evenafter implementing the second balancing three times. After that, thecontrol part notifies the user of an abnormal state of the laundrymachine.

As described above, when the drum is accelerated in the acceleratingstep, the irregular vibration of the drum may be sensed by using theunbalance of the drum, rather than using the vibration sensor. That is,if the vibration sensor is not provided in the laundry machine or it isout of function, the control part may sense the unbalance of the drum todetermine whether the irregular vibration is generated in the drum.Specifically, the control part senses the unbalance amount of the drum.If the sensed unbalance amount is increased to a predetermined value ormore, with maintained for a predetermined time period or longersimultaneously, the control part determines that the irregular vibrationis generated in the drum.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

INDUSTRIAL APPLICABILITY

The present invention has an industrial applicability.

According to the spinning cycle control method of the laundry machinedescribed above, if the vibration of the drum is a predetermined valueor more at the RPM higher than the transient region, the vibration ofthe drum may be reduced in the laundry machine having the vibration ofthe drum separated from that of the tub.

1. A control method of a laundry machine comprising a balancer, thecontrol method comprising: decreasing a speed of a drum in casevibration of the drum sensed in an accelerating step is a predeterminedvalue or more; and rotating a drum at a constant speed for apredetermined time period to implement balancing.
 2. The control methodas claimed in claim 1, wherein the balancing is implemented after thespeed of the drum passes a transient region of the laundry machine. 3.The control method as claimed in claim 1, wherein the accelerating stepcomprises two accelerating steps, and each of the two steps sense thevibration of the drum configured to implement the balancing.
 4. Thecontrol method as claimed in claim 3, wherein the accelerating stepcomprises a first accelerating step and a second accelerating step andeach of the first and second accelerating steps has a different targetRPM.
 5. The control method as claimed in claim 1, further comprising: abalancing step after the rotation speed of the drum passes the transientregion and before the drum enters into the accelerating step.
 6. Thecontrol method as claimed in claim 1, further comprising: completing thespinning cycle and notifying a user of the completion of the spinningcycle, when the vibration of the drum is sensed a predetermined numberof times or more.
 7. The control method as claimed in claim 1, whereinthe laundry machine comprises a driving unit comprising a shaftconnected to a drum, a bearing housing to rotatably support the shaft,and a motor to rotate the shaft, and a suspension assembly is connectedto the driving unit.
 8. The control method as claimed in claim 1,wherein the laundry machine comprises a rear gasket for sealing toprevent washing water from leaking from a space between a driving unitand a tub, and enabling the driving unit movable relative to the tub. 9.The control method as claimed in claim 1, wherein a tub is supportedrigidly more than a drum being supported by a suspension assembly.